Lack of Sleep May Impair Ability to Regulate Emotions
Sleep deprivation may alter emotional processing, making it more difficult to keep one’s emotions in check, according to a study in the September 23 issue of The Journal of Neuroscience.
Previous studies have shown that sleep deprivation makes the emotional centers in the brain more responsive to negative experiences and may also impair decision-making. But little is known about how sleep deprivation works to alter the brain’s ability to regulate its response when faced with an emotional challenge.
For the study, researchers from Tel Aviv Sourasky Medical Center and Tel Aviv University used functional magnetic resonance imaging and arrays of EEG electrodes to record the brain activity of 18 volunteers while they performed a task that required them to memorize sets of numbers while ignoring distractions. The numbers were superimposed on distracting pictures that were either unpleasant or neutral, creating a need for participants to regulate their emotional response in order to successfully perform the task.
Each volunteer completed the memorization task on two different days: once following a normal night’s sleep of 7 to 9 hours and again after being kept awake for 24 hours straight. During the scan, researchers monitored the activity of the amygdala, a part of the brain that processes emotions, and of areas of the prefrontal cortex that are responsible for regulating emotional responses.
When well-rested, the subjects responded strongly to the negative pictures, with strong activity in the amygdala, as expected. Neutral images did not elicit an emotional response. However, after 24 hours of wakefulness, the subjects’ scans showed similarly high levels of activity in the amygdala for both emotional and neutral photos, suggesting emotional hyper activation without sleep. At the same time, activity was significantly reduced in the prefrontal cortex.
A review of the subjects’ sleep records found that such hyper-emotional reactions were linked to lower amounts of rapid eye movement (REM) sleep, supporting a role for REM sleep in emotional processing.
Together, the findings suggest that a sleepless night can cause people to overreact to everyday challenges by lowering the brain’s threshold of emotional activation, the study's authors say. Additionally, the findings suggest a connection between sleep deprivation and anxiety. “Studies have shown that losing emotional neutrality is a hallmark symptom of anxiety disorders,” said Eti Ben-Simon and Talma Hendler the study’s leading authors. “These findings support a long-standing observation in sleep research that demonstrates how people become increasingly anxious without sleep.”
The Journal of Neuroscience is published by the Society for Neuroscience, an organization of nearly 40,000 basic scientists and clinicians who study the brain and nervous system. Study authors Eti Ben-Simon and Talma Hendler can be reached at etoosh@gmail.com and hendlert@gmail.com, respectively. More information on sleep and the brain can be found on BrainFacts.org.
